Method of producing cold in an absorption-type refrigerating plant performing this method

ABSTRACT

A method and apparatus for causing refrigeration use an absorbent which is directed in a primary flow for regeneration into a zone where it is superheated with a high-temperature heat transfer medium; the pressure within this zone is raised to prevent boiling-up of the superheated absorbent; the latter is returned from the superheating zone in a counterflow in respect of the primary relatively cold flow of the absorbent toward the superheating zone; the pressure of the return flow is reduced in a step-wise fashion in successive stages of the flow, the pressure being reduced in each said stage so as to ensure momentary boiling-up of the absorbent at the given respective temperature thereof. In each of the stages the coolant vapor produced is made to condense with transfer of heat to the adjacent relatively cold flow of the absorbent on its way to the superheating zone. The apparatus includes a multi-stage regenerator, wherein each of the stages is made up by a pack of perforated plates, the pressure reduction stages being grouped into two separate sections.

tlnite States Patent Ainbinder et al.

[ Dec. 30, 1975 METHOD OF PRODUCING COLD IN AN ABSORPTION-TYPEREFRIGERATING PLANT PERFORMING THIS METHOD {76] Inventors: EmmanuilGershkovich Ainbinder,

bulvar Pushkina, 7, kv. 8; Georgy Vasilievich Kurilov, ulitsaUniversitetskaya, 97, kv. 21; Leonid Sergeevich Neustroev, ulitsaArtema, 127, kv. 42, all of Donetsk, U.S.S.R.

[22] Filed: July 22, 1974 {21] Appl. No.: 490,864

Related U.S. Application Data [63] Continuation of Ser. No. 424,737,Dec. 14, 1973, abandoned, which is a continuation of Ser. No. 331,358,Feb. 12, 1973, abandoned, which is a continuation of Ser. No. 204,108,Dec. 2, 1971, abandoned.

[52] U.S. C1. 62/101; 62/476; 62/497;

[51] Int. Cl. FZSB 15/06 [58] Field of Search 62/101, 109, 476, 497;

[56] References Cited UNITED STATES PATENTS 3,146,177 8/1964 Chalmers etal 202/173 X 3,228,859 1/1966 Frankel et a1. 159/2 MS 3,287,928 11/1966Reid, Jr. 62/476 X 3,306,346 2/1967 Othmer 62/101 X Primary Examinerwilliam 1F. ODea Assistant ExaminerPeter D. Ferguson Attorney, Agent, orFirmHolman & Stern [57] ABSTRACT A method and apparatus for causingrefrigeration use an absorbent which is directed in a primary flow forregeneration into a zone where it is superheated with a high-temperatureheat transfer medium; the pressure within this zone is raised to preventboiling-up of the superheated absorbent; the latter is returned from thesuperheating zone in a counterflow in respect of the primary relativelycold flow of the absorbent toward the superheating zone; the pressure ofthe return flow is reduced in a step-wise fashion in successive stagesof the flow, the pressure being reduced in each said stage so as toensure momentary boiling-up of the absorbent at the given respectivetemperature thereof. 1n each of the stages the coolant vapor produced ismade to condense with transfer of heat to the adjacent relatively coldflow of the absorbent on its way to the superheating zone. The apparatusincludes a multi-stage regenerator, wherein each of the stages is madeup by a pack of perforated plates, the pressure reduction stages beinggrouped into two separate sections.

8 Claims, 4 Drawing Figures l7 2/ 26 r 74 I A 2W r J US. Patent Dec.30,1975 Sheet1of2 3,928,983

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US. Patent Dec.30, 1975 Sheet2of2 3,928,983

na U III:

METHOD OF PRODUCING COLD IN AN ABSORPTION-TYPE REFRIGERATING PLANTPERFORMING THIS METHOD This is a continuation, of application Ser. No.424,737, filed Dec. 14, 1973, now abandoned which in turn is acontinuation ofSer. No. 331,358 filed Feb. 12, 1973, now abandoned,which in turn is a continuation of Ser. No. 204,108 filed Dec. 2, 1971,now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention The presentinvention relates to a methods and apparatus for producing coldtemperatures and refrigeration, and, more particularly, the inventionrelates to absorption-type lithium bromide refrigerating plantsemploying high-temperature heat transfer media as the source of heat.

2. Description of Prior Art It is widely known that the existingabsorptionftype lithium-bromide refrigerating plants operate withextraction of the condensation and absorption heat with the help ofwater derived from water supply. Therefore, when large refrigeratingplants of this type are constructed and operated, the problem ofproviding therein either recycled or flowing-through cooling waterinvolves relatively great capital investment and a high operation cost,which makes the aim of cutting down the consumption of cooling water bylithium absorption-type refrigerating plants a truly pressing one.

At present, efforts aimed at cutting down the consumption of recycledwater by lithium bromide absorption-type refrigerating plants areconcerned with reducing the thermal load of the condenser, e.g. byintroducing double-stage regeneration and by stepping up the overalltemperature level of heat extraction, for instance, by employingmulti-stage systems.

Known solutions of the above said problem improve the economicalfeatures of the plant, but they however necessitate extraction of thecondensation heat from the coolant being condensed into the ambientatmosphere consequently, greater the economical characteristic of theiroperation, the smaller is (under comparable conditions) the differencebetween the temperature of the medium being cooled and that ofcondensation.

It should be also stated here that the existing systems of both recycledand flow-through cooling water supply involve not only wastage ofconsiderable quantities of water, but also the waste of a huge amount oflowpotential heat.

A number ofindustries that consume artificial cold at temperatures above0C, such as metallurgical, chemical, cokechemical, petro-chemical,meat-processing, dairy, food-industries, etc. offer a considerableamount of waste heat in the form of hot chimney gases at temperature ofabout 300 to 400C, as well as in theform of coke-oven gas, blast-furnacegas and other combustible gases, or else they operate on natural gas.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide a method of producing cold and an absorption-type refrigeratingapparatus which utilises high-temperature heat, the apparatus beingcapable of round-the-year operation for production of artificial heatand of hot 2 water for technological and sanitary purposes. In therefrigeration plant described and claim herein, the lower thetemperature of the water being cooled, the higher the economicalcharacteristic of the operation of the plant (under comparableconditions).

It is another object of the present invention to create a method ofcausing refrigeration and an absorptiontype lithium bromiderefrigerating plant, which employs high-temperature heat and operateswithout the use of recycled water from water supply, but with the use ofair-cooling, and with or without the employment of an intermediate heattransfer medium.

It is also an object of the present invention to provide a method ofrefrigeration and an absorption-type plant that employs high-temperatureheat and is capable of replacing the cooling systems for recycled watersupply in industrial enterprises, the absorption type plant describedherein is capable of replacing heat-supply boilers for production ofeither hot or superheated water.

It is yet another object of the present invention to broaden the fieldof applications of absorption-type lithium-bromide refrigerating plants,by utilizing them for generation of low temperatures either below orapproximating 0C.

The present invention attains these and other objects and resides in amethod of causing refrigeration and cooling, comprising the steps ofabsorbing the vapor of a coolant, evaporating subsequently said coolantfrom the absorbent, directing said absorbent into a superheating zonewith the help of a high-temperature heat transfer medium, raising thepressure within said zone to prevent boiling-up of said superheatedabsorbent, reducing said pressure in a step-wise fashion in successivestages at successive portions of the flow of said absorbent startingfrom the superheating zone, the pressure in each said stage beingreduced so as to provide for momentary boiling-up of said superheatedabsorbent at the respective given temperature thereof, the method beingcharacterized in that said superheated absorbent is returned from saidsuperheating zone in a counterflow in respect of the primary flow ofsaid absorbent toward said superheating zone, so that the vapor of saidcoolant produced at each stage of said return flow condenses and effectsheat transfer within said stage to the adjacent relatively cold primaryflow of said absorbent toward said superheating zone.

In accordance with the invention, the primary flow of the absorbent mayinclude independent successively supplied flows of absorbent that haveabsorbed the coolant vapor at different pressures.

In accordance with a preferred embodiment of the invention, saidabsorbent is an aqueous solution of lithium bromide, and said coolant iswater.

In accordance with the present invention, an absorption-typerefrigerating plant performing the abovedescribed method includes anevaporator of the coolant, the vapor of said coolant being absorbed inan absorber by a liquid absorbent, said liquid absorbent beingsubsequently directed into a regenerator subdivided into a plurality ofstages wherein the pressure is reduced in a step-wise fashion, startingfrom the superheating zone, the plant being, characterized by saidregenerator having therein a plurality of passages for the passagetherethrough of the primary flow of said absorbent toward saidsuperheating zone, and also for the passage of the return flow of saidsuperheated absorbent flowing in a counterflow in respect of saidprimary flow, as well as a plurality of passages for the passage of thecondensate, there being provided at the successive portions of saidreturn flow passages and condensate passages means for reduction of thepressure, said pressure-reducing means subdividing said regenerator intosaid Stages, each said stage, starting from said superheating zone,communicating with the next successive stage for separately directingthereinto said absorbent and said condensate.

In accordance with an embodiment of invention, the plant describedherein has said pressure-reducing means in the form of hydraulic seals.

In accordance with one of the embodiments ofthe invention, each saidstage of said regenerator plant includes a pack of assembled platesseparated by gaskets and having apertures made therethrough, theseapertures serving together with said passages for the passage of theabove heat transfer media and said condensate.

In a plant embodying the invention said hydraulic seals between saidstages may include each a gasket defining on the adjacent extreme one ofsaid plates a vertical conduit establishing communication between therespective pair of said adjacent stages, the height of said verticalconduit determining the value of the pressure drop between said stages.A plant embodying the invention, when it includes different absorbermeans adapted to absorb the vapor of said coolant at differentpressures, may have said regenerator thereof so constructed that saidstages thereof are grouped into two separate sections, the second one ofsaid sections in the direction of the flow of said absorbent which isregenerated being included into the flow path of said primary flowintermediate of said absorber means, the first one of said sectionscommunicating with that one of said absorber means which is operated ata relatively higher pressure.

The above improvements ensure elimination of the aforesaid drawbacks ofthe prior art refrigerating plants.

BRIEF DESCRIPTION OF THE DRAWING The present invention will be furtherdescribed in connection with a preferred embodiment thereof, withreference being had to the accompanying set of drawings, wherein:

FIG. 1 shows a schematic diagram of a plant embodying the invention,wherein heat extraction is performed with the help of an intermediateheat transfer medium;

FIG. 2 shows a schematic diagram of a plant embodying the invention,wherein heat is extracted from the apparatus directly into ambient air;

FIG. 3 shows a schematic diagram of a refrigeration plant embodying theinvention, adapted to produce cold at temperatures about and below zerodegree centrigrade; 7

FIG. 4 illustrates the regenerator of the plants shown in FIGS. 1 to 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description ofthe embodiment of the present invention illustrated in FIGS. 1 to 4various specific terms and expressions are used for the sake of clarity;however, the invention is in no way meant to be limited by thesespecific terms and expressions which are understood to embrace all theequivalents thereof operating in a similar manner and used for purposessimilar to those of the present invention. The apparatus to be describedhereinbelow can be employed for operation of the plant, as a whole, inaccordance with any one 'of the diagrams illustrated in FIGS. 1 to 3;the switchingover from the operating mode to another being effected bycorrespondinng re-connection of the solution conduits establishingcommunication between the apparatus.

Referring now in particular to the appended drawings, generation of lowtemperatures by refrigeration is effected within an evaporator l. Theevaporator l incorporatesheat exchange tubes 2 and a sprinkler device 4;it is associated with a pump 3. Extraction of heat from the coolantcirculating in the form of the refrigerant is effected within the tubes2.

This extraction of "heat from the coolant is brought about byevaporation of recirculation water supplied by the pump 3 and'sprinkledover the tubes 2 of the evaporator l.

The water vapor thus produced passes into an absorber 5 wherein it isabsorbed by the relatively rich solution of an absorbent, sprinkled by asprinkler device 6 over heat exchange tubes 7.

The solution of the absorbent, which is diluted because of reducedconcentration on account of absoption of the coolant vapor, is fed fromthe absorber 5 by a pump 8 for regeneration into a heater 9 through thepassages 10 of a regenerator 11. In order to prevent boiling-up of thesolution within the passages 10 and in the heater 9, the dilutedsolution is supplied for regeneration under gauge pressure which isabove the saturation pressure of the solution at the outlet of theheater.

The solution of the absorbent after being heated up is fed through athrottling device 12 into the passsages 13 of the regenerator 11, thepassages being meant for the flow of the superheated absorbent.

' The regenerator 11 also includes passages 14 for collection andremoval of the condensate produced on account of evaporation of thereturn flow of the absorbent through the passages 13.

The passages 13 and 14 are divided by respective throttling devices intoa plurality of successive portions (i.e. stages) for rapid boiling-up ofthe return flow of the absorbent, with corresponding stage-wisereduction of the pressure thereof, the coolant vapor produced in each ofthe stages condensing with transfer of heat into the relatively coldinitial flow of the absorbent through the passages 10.

Owing to the repeated boiling-up, the concentration of the absorbent inthe return flow is increased.

The richer solution of the absorbent is fed from the outlet stage, i.e.from the last boiling-up stage of the regenerator 11 through aheat-exchanger 15 into an absorber 16.

The absorber 16 is meant for absorption of the water vapor coming froman evaporator 19. Thelatter effects extraction of heat from the absorber5 by evaporation of water pumped through the tubes 7 of the absorber 5,this water being distributed in the evaporator 19 by a sprinkler device21. The pressure within the evaporator 19 is higher than that within theevaporator 1, whereby the pressurewithin the absorber 16 is higher thanthe pressurewithin the absorber 5. Therefore, in the following part ofthe disclosure the absorber 16 and the evaporator 19 will be referred toas the high-pressure apparatus, while the absorber'S and'the evaporator1 will be "referred to as the low-pressure apparatus".

The heat exchanger 15 effects cooling down of the rich-concentrationsolution of the absorbent to a temperature approximating the absorptiontemperature within the absorber 16. i

The absorbent solution the concentration of which has been partlyreduced within the absorber 16, is fed by the pump 22 for cooling downin a heat-exchanger 23, where from it is directed into the absorber 5.Within the absorber 5 the absorbent solution performs is absorbingaction at a pressure that is lower than that within the absorber 16. ltabsorbs the coolant vapor produced within the evaporator 1 from therecirculation water, as heat is being extracted from the heatedup coldtransfer medium.

The evaporators 1 and 19 are associated with means for directingthereinto the condensate from the regenerator ll.

For extraction of heat from the plant shown in FIG. 1 there is provideda water cooling device 24.

Water cooled down in the water cooling device 24 is pumped for heatextraction by a pump 25 through the heat-exchanger 23, through the tubes18 of the absorber l6 and through the heat-exchanger l5, whereafter itreturns into the water cooling device 24. Cooling air is blown throughthe water cooling device 24 by a separately provided blower or fan means(not shown in FIGS. 1 to 3).

The absorber l6 and the heat exchangers l5 and 23 may have direct aircooling as is shown in FIG. 2. In this case these apparatus areassociated either with individual air blower means or with a common one,for extraction of heat (the air blower or fan means are not shown inFIG. 2), and the apparatus per se is either of a multitube or of afinned plate structure, i.e. the apparatus includes a developed surfacefor contact with the cooling air.

When a plant embodying the present invention is to be operated forproducing temperatures below 0C or temperatures approximating 0C (seeFIG. 3), the regenerator 11 is sub-divided into two sections A" and B,to be connected to accomodate the primary flows of the absorbent throughthe passages of these sections A and B, respectively, to thelow-pressure absorber 5 and to the high-pressure absorber 16. The returnflow of the absorbent, that successively passes through the boiling-upstages of the passage 13 of the sections A and B, is cooled within theheatexchanger to a temperature approximating the initial temperature ofabsorption within the absorber 5. The absorbent solution theconcentration, of which has been brought down in the absorber 5, ispumpedby the pump 8 into the passages 10 of the section B of theregenerator 11, wherein it is heated up by the condensation heat of thevapor of the coolant which is vaporized in the passages 13 of thissection of the regenerator l 1.

In order to prevent freezing'of the recirculation water and of the coldtransfer medium, when the herein disclosed plant is operated to producetemperatures below zero, the recirculation water is replaced eitherby'an alkaline solution (such as KOH or LiOI-l), or else by a weaksolution of LiBr.

The coolant condensate is returned into the evaporators (see FIGS. 1 to3) through loop-type hydraulic seals 26 and 27. The condensate from theregenerator 11 is directed into the evaporator 19, wherefrom it isdirected into the evaporator l.

The abovementioned passages 10, 13 and 14 of the regenerator 14 aredefined by a series of similar parts, illustrated in greater detail inFIG. 4. v

Boiling-up of the return flow of the absorbent solu' tion takes place inhollow closed passages 28 including: a conduit 29 for the passagetherethrough of the initial poor-concentration solution of theabsorbent, a conduit or pipe 30 for producing a hydraulic seal in eachsuccessive evaporation panel relative to the preceding one, a capmember, or conduit 31 for producing a downflow of the boiling-upsolution, an aperture a for removal of the coolant vapor produced, anaperture b for introduction of the return flow of the absorbent into thepipe 30, an aperture c for removal of the boiled-up absorbent solution.

Condensation of the coolant vapor takes place over the surface of thepack of plates associated with the evaporation panel through a gasket32. The pack of plates is made up by plates 33, 34 and gaskets 35, 36.

The plates 33 and 34 have the following apertures made therethrough:

' aperture a for the passage of the coolant vapor;

aperture c for removal of the boiled-up absorbent solution;

aperture e for removal of the condensate;

aperture d for the passage of the primary poor-concentration flow of theabsorbent.

The gaskets 32, 35 and 36 are provided with apertures a, c, e, d formedtherethrough and arranged continuously with the similarly designatedapertures in the plates 33 and 34.

Condensation of the coolant vapor takes place in a space defined by thepanel 28, the gasket 32 and the plate 33, as well as by the-adjacentplates 34 and gaskets 35. The passage of the vapor is ensured by theprovision in each of the above members of the aperture a. The extractionof the condensation heat of the coolant vapor is effected into the flowof the absorbent through the space between the plates 33 and 34, definedby the gasket 36.

The coolant condensate is directed through the respective apertures e inthe above plates and gaskets toward the blind wall of the nextsuccessive return flow evaporation panel 28. Supply of the condensateinto the next successive condensation stage is effected through ahydraulic seal provided by a gasket 37 defining together with thelast-in-the-series plate 33, i.e. with the plate 33 adjoining the nextsuccessive panel 28, a vertical passage establishing communicationbetween the adjacent stages through the conduit 31.

The vertical extent or reach of the last-mentioned vertical passagedetermines the pressure drop between the adjacent stages, because, onaccount of the density of the absorbent solution being substantiallyhigher than the density of the coolant, the hydraulic seal of theconduit 30 can be selected to provide for a greater pressure dropbetween the adjacent stages 'than the pressure drop effected by theabove hydraulic seals and affecting the condensate. The passages of theregenerator 11 (FIGS. 1 to 3) are thus defined by the assembly of theabovedescribed structural parts illustrated in FIG. 4.

The passage 10 for the primary flow of the absorbent is defined by theconduit 29 continuous with the apertures d in the gasket 32 and in. theplate 33, by the gaps defined between the adjacent plates 33 and 34 bythe gasket 36, by the apertures d in the bottom right-hand corners ofthe plate 34, gasket 35 and plate 34 adjacent to the last-mentionedgasket on the side of the return flow, by the next successive gapbetween the plates 34 and 33 and the gasket 36, by the apertures d inthe upper left-hand corners of the plate 33 and in the gas ket 32interposed between this plate 33 and the successive panel 28, by theconduit 29 in the panel 28. Thus, the conduit 29 provides for thepassage of the primary flow from the passage of one stage of theregenerator 11 into the passage 10 of the next successive stage, in thedirection of the primary flow.

The passage for the return flow of the absorbent is made up by theaperture b in the panel 28, by the conduit 30, by the internal cavity ofthe panel 28, by the apertures c in the gaskets 32, 35, 36 and in theplates 33, 34 associated with the panel 28, by the aperture b in thenext successive panel 28, by the conduit 30 in the last-mentioned panel,and so on, until from the panel 28 which is the last in the successionin the direction of the return flow the rich-concentration solution ofthe absorbent is directed toward the high pressure absorber 16.

The passage 14 for collection and removal of the condensate is definedby the wall of the panel 28 with the aperture a, by the adjacent gasket32, by the plate 33, by the apertures e in the plates 33 and 34, by theapertures e in the gaskets 36 and by the space defined by the gasket 37in the gap between the blind wall of the next successive return flowevaporation panel 28 and the plate 33 adjacent thereto. Through saidpassage 14 the condensate is supplied toward the conduit 31 whichdirects it into the next successive condensation stage.

The abovedescribed sets of the evaporation panels, gaskets and plates,shown in FIG. 4, are assembled into packs, or stacks.

Production of cold temperature in the herein disclosed plant, with theemployment of an intermediate heat transfer medium for extraction ofheat from the apparatus, as shown in FIG. 1 of the appended drawings, iseffected in the following way.

Within the tubes 2 of the evaporator 1 heat is extracted from the waterthat has been heated up, in the consumer of cold by the recirculationwater sprinkled over the tubes 2. Thus, the heat supplied to therecirculation water from the consumer of cold is partly spent onevaporation of the last-mentioned water. The water vapor thus produced(i.e. the coolant vapor) is absorbed by the absorbent solution, which isan aqueous solution of a relatively rich concentration, within theabsorber 5. Absorption of the water vapor by an aqueous solution oflithium bromide (LiBr) takes place when there is a definite positivedifference between the water vapor pressure in the evaporator 1 and inthe absorber 5, in the absence of non-condensible gases.

As a result of the absorption of the water vapor, the absorbent solutionis heated up, and the concentration, thereof diminishes, whereby itbecomes incapable of absorbing water vapor at the pressure within theabsorber 5.

Extraction of the heat of the absorption of the cool water vapor fromthe low-pressure evaporator 1 is effected in the high-pressureevaporator 19 by evaporating of the water recirculated through thecoiled tubes 7 of the absorber 5 sprinkled with a LiBr solution.

The poor concentration solution is directed from the absorber 5 (theconcentration being, e.g. 54% 56% at a temperature of 30 to 40C) under ahigh pressure into a superheating zone, for the supply thereto of theheat necessary ,for increasing the concentration of the solution byevaporation of the coolant that has been absorbed within the absorbers 5and l6.

The superheating zone is formed by the passage 10 of the regenerator 11(FIG. 1 to 3), the heater 9 and the throttling device 12. At this zone,the solution is first heated to -lOOC within the passage 10, whereafterit is heated to 200230C within the heater 9 and reduced into thesuperheated condition in the throttling device 12. The superheatedreturn flow of the absorbent solution is introduced into the first panel28 through the conduit 30. Boiling-up of the solution in the evaporationpanels is determined by the condensation pressure of the coolant vaporin the passage 14 adjoining the panels (FIGS. 1 to 3). The condensationpressure in the passages 14 is determined by the number of the stages ofevaporation of the solution, by the heat exchange conditions and by theinitial temperature of the primary flow of the solution, fed into thepassage 10.

The partly strengthened solution is directed from the abovementionedpanel 28 through a passage formed by the apertures in the adjacentplates and gaskets (see above) into the conduit 30 of the nextsuccessive panel 28. The conduit 30 acts as a hydraulic seal along theline of the return flow of the solution between each successiveevaporation stage in relation to the preceding one.

Condensation of the vapor takes place in the passages 14 (FIGS. 1 to 3)over the surface of the adjacent pairs of the plates 33 and 34 (FIG. 4),with the condensation heat being turned over to the primary flow of therelatively weak solution directed under pressure between the said platestoward the heater 9.

The condensate from each section of the evaporation (condensation)stage, i.e. the condensate produced on account of evaporation of thecoolant from the return flow of the absorbent solution, is collectedadjacent the successive panel 28 through the corresponding apertures(see above) in the pack of the plates and gaskets and is directed intothe successive stage through the passage formed by the adjacent plate33, gasket 37, panel 28 and conduit 31. This passage acts as a hydraulicseal of each evaporation stage in relation to the preceding one alongthe condensate flow line.

It should be noted here that it is possible to replace the conduits 30in the panels 28 by conduits similar to those effecting direction of thecondensate, and it is also possible to replace the evaporation panelsthemselves by two plates and one gasket per each panel.

As a result of self-evaporation of the return flow of the absorbent, asit passes successively from a preceding evaporation panel into asuccessive one at a pressure that is reduced stage-wise, in accordancewith the temperature of the condensation of the vapor in each respectivestage of the regenerator 11, and of condensation of the coolant vapor bythe relatively cool primary flow of the absorbent solution pumpedthrough the passages 10 (FIGS. 1 to 3), there is effected regenerationof the initially relatively weak absorbent solution flow without theemployment of an external cooling medium for condensation of the coolantvapor.

This means that the operation of the regenerator 11 is more economical(under comparable conditions), with the cold temperature produced beingsimultaneously brought down, because the temperature of the weaksolution taken from the absorber 5 and directed into the passage 10 ofthe regenerator 11 is reduced. The reduction of the initial temperatureof the primary flow of the solution at the inlet of the passage 10 leadsto broadening of the degassing zone, thereby causing 9 increase in thecold temperature produced. The strengthened solution of LiBr fromlast-in-the-succession panel 28 (along the return flow of the absorbent)and the condensate from the pack of the plates and gaskets adjacent tothis panel are directed, respectively as follows:

the LiBr solution through the heat exchanger 15 where it is cooled by20C 30C into the absorber 16;

the condensate into the evaporator 19 through the loop-type hydraulicseal.

The strengthened solution flows into the absorber 16 through the heatexchanger 15 by gravity, owing to the regenerator l 1 being positionedabove the absorber 16. Within the latter the LiBr solution absorbs watervapor at a relatively high pressure from the evaporator 19. Theabsorption heat of the coolant vapor is extracted by the watercirculated through the tubes 18 sprinkled with the solution. Theweakened LiBr solution is subsequently supplied by the pump 22 into theabsorber 5, for absorption of the low-pressure coolant vapor. Prior tobeing fed into the absorber 5, the solution is cooled in theheat-exchanger 23 by 20 to 30C.

After having passed through the hydraulic seal into the evaporator 19,the condensate from the regenerator ll boils up and cools down to asaturation temperature within this evaporator 19. A portion of thecondensate, necessary for maintaining a permanent level of therecirculation water in the evaporator 1, is directed into the latterthrough the loop-type hydraulic seal. In this way the closed flow of thecoolant in the herein disclosed plant is completed.

The removal of the heat supplied to the herein disclosed plant in theevaporator and in the heater is effected:

in the heat exchanger 15 at temperatures of the solution within 1 10 to80C;

in the absorber 16 at solution temperatures within 80 to 70C;

in the heat exchanger 23 at solution temperatures within 70 to 45C.

The extended range of the temperatures of the heat removed from theherein disclosed plant and the possibility of withdrawing not less than70 percent of this heat at temperatures above 70C in the hereindisclosed plant offer a wide variety of applications involvingsimultaneous production of cool and hot water for practical purposes.

In addition to the abovementioned heat exchangers l and 23, the linealong which the LiBr solution is supplied into the absorber 5 and intothe passage of the regenerator 11 may be associated, for the sake ofgreater economy, with other auxiliary means for cooling down thesolution, e.g. those employing air or water, and those .using aircooling combined with water evaporation, etc. (these auxiliary coolingmeans are not shown in FIGS. 1 to 3).

The operation of the herein disclosed plant without the use of theintermediate heat transfer medium for heat extraction, illustrated inFIG. 2, is basically similar to that described hereinabove. However, inthe plant shown in FIG. 2 heat is extracted from the plant directly intothe ambient atmosphere at the finned tubes of the heat exchangers 15, 23and of the absorber 16.

When the plant is operated according to the mode illustrated in FIG. 2,the heat extracted therefrom can be utilized only in the form of hot airat temperatures 60 to 70C. Therefore, in cases when it is desirable toproduce refrigeration or cold temperature and also to satisfy customersin need of heat at temperatures from C to 100C, it is advisable toemploy the plant in accordance with FIG. 1. Alternatively, when eitherthe use of the extracted heat is impractical, or when there areconsumers of hot air, it is advisable to employ the plant illustrated inFIG. 2.

When the plant is operated for production of cold temperatures eitherbelow or approximating 0C (FIG. 3), there is used in the evaporator 1either a weak alkaline solution (KOH, Lioll-l) or a weak solution ofLiBr as the recirculation medium, instead of water, and the sections Aand 13" of the regenerator 11 are connected in series, as far as thereturn flow of the absorbent solution being strengthened and the flow ofthe coolant condensate are concerned, these sections A and B beingconnected in parallel in respect of the primary flow of the weak,relatively cool absorbent, namely:

the section A is connected to the low-pressure absorber 5; the section Bis connected to the high-pressure absorber 16.

Now the circulation of the LiBr solution through the system is asfollows: low -pressure absorber 5 pump 8 passage 10 of section A ofregeneration l1 heater 9 throttling device 12 passage 13 of regenerator11 heater l5 absorber 5. Similarly to the abovedescribed operation mode,the absorption heat of the low-pressure vapor from the evaporator l isfirstly extracted by evaporation of water in the evaporator 19 andsecondly, by absorption of the thus produced vapor in the high-pressureabsorber at a higher temperature level. The condensate from theregenerator 11, as it has been mentioned hereinabove, is directed intothe evaporator 19, wherefrom it is directed into the evaporator l forcompleting the closed path of the coolant within the plant.

In this case the heat removed from the consumer of cold and thatsupplied to the heater is extracted in two regions of the apparatus,namely:

in the heat exchanger 15 at solution temperature within 100C 45C;

in the absorber 16 at solution temperature within 60 to C.

The withdrawal of air and of uncondensible gases from the hereindisclosed plant is performed in the following sequence: from theabsorber 5 into the absorber l6 and then into the atmosphere. Withdrawalof air from the regenerator-condenser line is effected by blowingthrough the condensation sections into the evaporator 12. Means forwithdrawing uncondensible gases are not shown in FIGS. 1 to 3.

It should be borne in mind that the embodiment of the inventiondescribed hereinabove and illustrated in the appended drawings is but anexemplary embodiment; other embodiments and variations of the presentinvention are also possible and envisaged, differing from the onedescribed herein by the structure of individual apparatus, by thesolution circulation path, by the distribution of the solution among theabsorbers, by the employment of circulated water in the evap'orators, bythe path of circulation of the cooling water through the absorbers andevaporators.

The structure of the hereinabove described regenerator can likewise bemodified without departing from the scope of the invention, e.g.. thestructure may incorporate various regulators at different levels insteadof the hydraulic seals, said regulators being associated with automaticmeans for withdrawal of the solution and of the condensate from stagespreceding the last one, should be temperature of the solution at theinlet of the regenerator-condenser fall below a preset value.Furthermore, the plates used may be of various shapes and structures,special portions for flushing the vapor by the condensate may beprovided within the evaporation panels, and so on. Such modificationsare possible, if the following principal condition is satisfied:evaporation of the solution should be effected at a pressure that isreduced stage-wise, and the vapor is condensed at the weak solutiondirected in a counter-flow in respect of the solution beingstrengthened.

Plants constructed in accordance with the present invention can beemployed for operation with various absorbents that arenon-covaporizable with the solvent, and the heat extracted from theplant may be used for various purposes, including simple heating ofvarious media and various processes, such as vacuum deaeration of water.

As follows from the above disclosure, the expression absorption typerefrigeration plant that is used in the claims to follow is intended toinclude such equivalent as thermo-chemical compressor, thermaltransformer, heat-utilization plant, etc. that can be operated on theprinciple of the present invention.

What we claim is:

1. A method of producing low temperatures and causing refrigeration,comprising the steps of:

absorbing the vapor of a coolant with a liquid absorbent;

directing said absorbent into a primary flow into a superheating zonethereof with the help of a hightemperature heat transfer medium under ahigh pressure;

maintaining the high pressure within said superheating zone to preventboiling-up of the superheated absorbent; reducing the pressure in' astep-wise fashion in successive stages at successive portions of theflow of the absorbent, starting from the superheating zone, the pressurein each stage being reduced so as to provide for a momentary boiling-upof said superheated absorbent at a respective given temperature thereof;returning said superheated absorbent from said superheating zone incounterflow heat exchange with the primary flow of said absorbent towardthe superheating zone so that the vapor of said coolant produced at eachstage of said return flow condenses and effects heat transfer inside thestage with respect to the cold primary flow of absorbent toward saidsuperheating zone; and I returning the coolant condensate to anevaporator with a subsequent evaporation thereof at a low temperaturedue to the heat extracted from the object to be cooled and by absorbingthe cold vapors with the liquid absorbent which is to be cooled by anoutside source.

2. A method in accordance with claim 1, wherein said primary flow ofsaid absorbent includes independent successively supplied flows ofabsorbent that have absorbed said vapor of said coolant at differentpressures.

3. A method in accordance with claim 2, wherein said absorbent is anaqueous solution of lithium bromide and said coolant is water.

4. An absorption-type refrigerating plant using a coolant comprising:

evaporating means for evaporating the coolant;

absorbing means communicating through a vapor space to said evaporatingmeans for absorbing the vapor of said coolant with a liquid absorbant;

an absorbent regenerator subdivided by a throttle into an absorbentsuperheating zone under a high pressure and stages for successivestep-wise reduction of the pressure of said superheated absorbent, saidregenerator communicating in a primary flow and a return'flow with saidabsorbing means, said regenerator having a plurality of successivepassages for the passage therethrough of the primary flow of saidabsorbent towards said superheating zone, an additional passage for thepassage therethrough of the return flow in successive stages of saidsuperheated absorbent directed in a counterflow to the primary flow, anda plurality of passages for the flow of a condensate;

means provided at said successive stages of said return flow passage andat least some of said condensate passages for reducing the pressure ofsaid return flow of absorbent and said condensate, said meanssubdividing said regenerator into said successive stages, each stagestarting from said superheating zone being associated with a successiveone of said stages for a separate passage of said absorbent and saidcondensate;

pipes for returning the coolant condensate to said evaporating means fora subsequent evaporation thereof at a low temperature due to the heatextracted from the object being cooled and for returning the coolantvapor to said absorbing means, pipes for returning of strengthenedabsorbant to absorbing means of the vapor of said collant; means forcooling the liquid absorbant; and means for heat exchange between thevapor of said coolant of return absorbent flow and said primaryabsorbent flow.

5. A refrigerating plant in accordance with claim 4, wherein said meansfor pressure-reducing comprise hydraulic seals.

6. A refrigerating plant in accordance with claim 5, wherein each saidstage of said regenerator includes a pack of plates separated by gasketsand having apertures made therethrough, said apertures making uptogether said passages for the passage of said primary and said returnflows and of said condensate.

7. A refrigerating plant according to claim 6, wherein each of saidstages includes a gasket defining on an adjacent extreme one of saidplates conjugated with the blind wall of an evaporating panel, avertical conduit communicating with each other a pair of said adjacentstages and having a predetermined height, the height of said verticalconduit determining the value of the pressure drop between said adjacentstages.

8. An absorption-type refrigerating plant using a coolant, comprising:

evaporating means for evaporating the coolant;

absorbing means communicating through a vapor said superheating zonebeing associated with said regenerator having a plurality of successivepassages for the passage therethrough of a primary flow of saidabsorbent to said superheating zone, an additional passage for thepassage therethrough of a return flow in successive stages of saidsuperheated absorbent directed in a counterflow to the primary flow, anda plurality of passages for the flow of a condensate;

means provided at said successive stages of said return flow passage andsaid plurality of condensate passages for reducing the pressure of saidreturn flow of absorbent and said condensate, said mean subdividing saidregenerator into said successive stages, each stage starting from saidsuperheating zone being associated with a successive one of said stagesfor a separate passage of said absorbent and said condensate; and meansfor heat-exchange between the vapor of said coolant of return absorbentflow and said primary absorbent flow;

said regenerator comprising stages thereof which are grouped into firstand second sections, the second one of said sections being disposed inthe primary flow on the flow path of the regenerated absorbent fromabsorbing means which is operated at relatively low pressure toabsorbing means which is operated at a relatively higher pressure, thefirst one of said sections being coupled to said absorbing means whichis operated at a relatively higher pressure.

1. A method of producing low temperatures and causing refrigeration,comprising the steps of: absorbing the vapor of a coolant with a liquidabsorbent; directing said absorbent into a primary flow into asuperheating zone thereof with the help of a high-temperature heattransfer medium under a high pressure; maintaining the high pressurewithin said superheating zone to prevent boiling-up of the superheatedabsorbent; reducing the pressure in a step-wise fashion in successivestages at successive portions of the flow of the absorbent, startingfrom the superheating zone, the pressure in each stage being reduced soas to provide for a momentary boiling-up of said superheated absorbentat a respective given temperature thereof; returning said superheatedabsorbent from said superheating zone in counterflow heat exchange withthe primary flow of said absorbent toward the superheating zone so thatthe vapor of said coolant produced at each stage of said return flowcondenses and effects heat transfer inside the stage with respect to thecold primary flow of absorbent toward said superheating zone; andreturning the coolant condensate to an evaporator with a subsequentevaporation thereof at a low temperature due to the heat extracted fromthe object to be cooled and by absorbing the cold vapors with the liquidabsorbent which is to be cooled by an outside source.
 2. A method inaccordance with claim 1, wherein said primary flow of said absorbentincludes independent successively supplied flows of absorbent that haveabsorbed said vapor of said coolant at different pressures.
 3. A methodin accordance with claim 2, wherein said absorbent is an aqueoussolution of lithium bromide and said coolant is water.
 4. Anabsorption-type refrigerating plant using a coolant comprising:evaporating means for evaporating the coolant; absorbing meanscommunicating through a vapor space to said evaporating means forabsorbing the vapor of said coolant with a liquid absorbant; anabsorbent regenerator subdiviDed by a throttle into an absorbentsuperheating zone under a high pressure and stages for successivestep-wise reduction of the pressure of said superheated absorbent, saidregenerator communicating in a primary flow and a return flow with saidabsorbing means, said regenerator having a plurality of successivepassages for the passage therethrough of the primary flow of saidabsorbent towards said superheating zone, an additional passage for thepassage therethrough of the return flow in successive stages of saidsuperheated absorbent directed in a counterflow to the primary flow, anda plurality of passages for the flow of a condensate; means provided atsaid successive stages of said return flow passage and at least some ofsaid condensate passages for reducing the pressure of said return flowof absorbent and said condensate, said means subdividing saidregenerator into said successive stages, each stage starting from saidsuperheating zone being associated with a successive one of said stagesfor a separate passage of said absorbent and said condensate; pipes forreturning the coolant condensate to said evaporating means for asubsequent evaporation thereof at a low temperature due to the heatextracted from the object being cooled and for returning the coolantvapor to said absorbing means, pipes for returning of strengthenedabsorbant to absorbing means of the vapor of said collant; means forcooling the liquid absorbant; and means for heat exchange between thevapor of said coolant of return absorbent flow and said primaryabsorbent flow.
 5. A refrigerating plant in accordance with claim 4,wherein said means for pressure-reducing comprise hydraulic seals.
 6. Arefrigerating plant in accordance with claim 5, wherein each said stageof said regenerator includes a pack of plates separated by gaskets andhaving apertures made therethrough, said apertures making up togethersaid passages for the passage of said primary and said return flows andof said condensate.
 7. A refrigerating plant according to claim 6,wherein each of said stages includes a gasket defining on an adjacentextreme one of said plates conjugated with the blind wall of anevaporating panel, a vertical conduit communicating with each other apair of said adjacent stages and having a predetermined height, theheight of said vertical conduit determining the value of the pressuredrop between said adjacent stages.
 8. An absorption-type refrigeratingplant using a coolant, comprising: evaporating means for evaporating thecoolant; absorbing means communicating through a vapor space to saidevaporating means for absorbing the vapor of said coolant with a liquidabsorbent at different pressures; an absorbent regenerator subdivided bya throttle into an absorbent superheating zone under a high pressure andstages for successive step-wise reduction of the pressure of saidsuperheated absorbent, said superheating zone being associated with saidregenerator having a plurality of successive passages for the passagetherethrough of a primary flow of said absorbent to said superheatingzone, an additional passage for the passage therethrough of a returnflow in successive stages of said superheated absorbent directed in acounterflow to the primary flow, and a plurality of passages for theflow of a condensate; means provided at said successive stages of saidreturn flow passage and said plurality of condensate passages forreducing the pressure of said return flow of absorbent and saidcondensate, said mean subdividing said regenerator into said successivestages, each stage starting from said superheating zone being associatedwith a successive one of said stages for a separate passage of saidabsorbent and said condensate; and means for heat-exchange between thevapor of said coolant of return absorbent flow and said primaryabsorbent flow; said regenerator comprising stages thereof which aregrouped into first and second sections, the second one of said sectionsbeing disposed in the primary flow on the flow path of the regeneratedabsorbent from absorbing means which is operated at relatively lowpressure to absorbing means which is operated at a relatively higherpressure, the first one of said sections being coupled to said absorbingmeans which is operated at a relatively higher pressure.